1. Field of the Invention
The present invention relates to digital cameras. More specifically, the present invention relates to a digital camera system employing digital holographic storage.
2. The Prior Art
Digital cameras are known in the art. Most such cameras employ charge-coupled device (CCD) or complementary metal oxide semiconductor (CMOS) imager arrays for generating image data which are then stored in digital semiconductor memory for later readout and viewing.
Holographic camera systems that use analog image storage are known in the art. U.S. Pat. No. 5,101,397 to Banjo discloses a method for recording signals on and reading signals from film. U.S. Pat. No. 5,144,461 to Horan discloses a portable holographic recording apparatus. U.S. Pat. No. 4,707,053 to Gurevich et al. discloses a recording device. U.S. Pat. No. 5,515,183 to Hashimoto discloses a real-time holography system. U.S. Pat. 4,735,474 to Allon discloses a photograph booth with automatic holographic camera. U.S. Pat. No. 4,376,950 to Brown et al. discloses a three-dimensional television system using holographic techniques.
According to a first aspect of the present invention, a digital holographic camera device, medium, reader, and system for recording photographs digitally and transferring the data to a computer or other digital device is disclosed. Preferably, a storage device, which comprises a removable cartridge containing a recording medium, is placed inside a digital holographic camera. Alternatively, a fixed medium may be employed. The medium is situated inside the camera in an appropriate manner so that digital data can be recorded onto it holographically. The medium comprises a photosensitive material capable of digital holographic recording, e.g. a photopolymer or photorefractive crystal. The medium can also comprise other layers, such as a substrate and protective layers.
Generally, picture data are first converted to a bit stream, which is then recorded onto the medium digitally using holographic storage techniques. The data can be buffered in solid-state memory prior to holographic recording. The holographic recording subsystem of the present invention can comprise, for example, a low-power laser and a spatial-light modulator. Multiple holograms can be recorded using techniques that include angular multiplexing, wavelength multiplexing, phase encoded multiplexing, and related multiplexing techniques that allow the storage of multiple holograms at the same spatial location. Additionally, multiple holograms can be recorded at multiple spatial locations. This can be facilitated, e.g., by including a media advance mechanism in the storage device, by designing the cartridge to facilitate media advance by the camera, or by optical beam steering. Linear and rotary advance mechanisms are suitable. The storage device may also take the form of a monolithic card.
The digital holographic camera according to the present invention can be designed for data recording only. The camera can also be designed to have readout capability to output recorded data directly. In the first case, the removable holographic storage device can be transferred to a dedicated reader. The removable holographic storage media cartridge, when used, is designed to transfer from the camera to the reader in a manner that keeps the media intact during the transfer i.e., light tight. The reader can have a media delivery mechanism, a low-power laser, an imaging lens as needed, and a detector array such as a CCD array or a CMOS detector array. Certain output configurations require an output imaging lens, and others do not. The reader can connect to a computer as a peripheral device or may be integrated into a computer. The reader can also be integrated directly into other devices, such as a printer dedicated to printing out photographs, so that the media can be read without the use of a computer.
In addition to photo data, the high capacity afforded by holographic data storage allows a host of other types of data to be stored digitally integrated with the photo data. Examples include voice annotation, date/location/exposure conditions/etc., and other information that describes the circumstances of the photo, as well as other data not necessarily related to the circumstances of the photo, such as music.
The data can be organized using variable formats in which a portion of the storage media records data using low resolution pixels and the rest of the media uses higher resolution pixels. An advantage of this process is that the level of resolution of a large section of the material can be identified by a dedicated low resolution region, so that as higher resolution cameras, media, and readers are introduced, low resolution media are compatible with high resolution media. The system of the present invention can use switch-out program cards to control operation, e.g. annotation, resolution control.
Using one or more flip-mirrors or additional beam splitters, the output light can alternately be directed to a view finder to view the recorded data.
From a user""s perspective, the digital holographic camera of the present invention can operate in a manner similar to a conventional film camera. The capacity of each cartridge can be based on current film packaging, which emphasizes film speed and count. For example, cartridges can be differentiated according to resolution in a manner similar to the distinction between high-speed and low-speed film, which generally have lower and higher resolution, respectively. By providing predetermined picture counts, e.g. 24 or 36, required capacity is based on count and resolution. The picture count can potentially be increased beyond levels available for typical film cartridges (e.g. 48, 64) in order to increase the attractiveness of the technology. Capacities on the order of 128 Mbytes would provide a distinct advantage over present capacities of 8-16 Mbytes for current flash memory cameras.
The present invention provides the ability to use low-cost, high-capacity media in a variety of form factor and data formats.
The present invention further provides the ability to incorporate high-capacity annotation, such as voice annotation, in digital form.
Additional advantages of the present invention include use of a digital page-based system in a digital camera; ability to play back data in the camera or separately outside the camera; possibility to reuse some camera components for image acquisition and display for page-based holographic storage.